A solid polymer electrolyte-type fuel cell is known as a form of fuel cell. Regarding such solid polymer electrolyte-type fuel cell, the fuel cell is formed by stacking a plurality of unit cells, in each of which a membrane electrode assembly (MEA) is sandwiched by separators respectively provided with air (oxygen) gas flow paths and fuel (hydrogen) gas flow paths.
It is known that impurities, such as organic matter, adhere to an anode and a cathode of a membrane electrode assembly (MEA) during the manufacture of a fuel cell (patent document 1). Thus, patent document 1 proposes that, during the aging performed when a fuel cell is shipped (initial running-in operation for a fuel cell), a positive electrode of a power source is connected to the cathode side while a negative electrode of the power source is connected to the anode side so as to cause the potential of the cathode to be higher than that of the anode, whereby the organic matter that has adhered to the cathode is removed.